This switcher works at a single resolution for all inputs. Typically 720p or 1080i. Most consumer camcorders output a 1080i signal, so I would select that.

Your Canon dslr (you did not specify which one) should work just fine at 1080i through the HDMI port. Sony HDV cameras typically do not have an HDMI or SDI port, but most have component cable support. Pickup a Black Magic converter and convert to HDMI or SDI and it will work just fine. I do this quite often with the Z1. I would select the SDI because of the longer and cheaper cable support. Also, input 1 on the ATEM can be configured for component input so you can connect directly on one input without a converter. Requires three coax cables, though.

Getting various cameras to work is just an exercise in matching resolutions and frame rates. The switcher is easy. Set it to 1080i and then work on camera settings. That may be more obscure.